/*

* Copyright (c) 2002-2009 Nokia Corporation and/or its subsidiary(-ies).

* All rights reserved.

* This component and the accompanying materials are made available

* under the terms of the License "Eclipse Public License v1.0"

* which accompanies this distribution, and is available

* at the URL "http://www.eclipse.org/legal/epl-v10.html".

*

* Initial Contributors:

* Nokia Corporation - initial contribution.

*

* Contributors:

*

* Description: 

*

*/

#include "des.h"

#include "destables.h"

#include "../common/inlines.h"

#include "des.inl"

#include <cryptostrength.h>

const TInt KDESBlockBytes = 8;

const TInt KDESKeyBytes = 8;

//	bit 0 is left-most in byte

static const TInt bytebit[] = {0200,0100,040,020,010,04,02,01};

void CDES::Transform(TDes8& aBlock)

	{

	assert(aBlock.Size() == KDESBlockBytes);

	TUint32 l, r;

	// Split the block into 2 word-sized big endian portions

	GetBlockBigEndian((TUint8*)&aBlock[0], l, r);

	IPerm(l,r);

	CDES::DoTransform(l, r, iK1);

	FPerm(l,r);

	// Put the portions back into the block as little endian

	PutBlockBigEndian((TUint8*)&aBlock[0], r, l);

	}

void CDES::DoTransform(TUint32& l, TUint32& r, const TUint32* aKey)

	{

	TInt i = 0;

	for (; i<8; i++)

		{

		TUint32 work = rotrFixed(r, 4U) ^ aKey[4*i+0];

		l ^= DES_TABLE::sbox[6][(work) & 0x3f]

		  ^  DES_TABLE::sbox[4][(work >> 8) & 0x3f]

		  ^  DES_TABLE::sbox[2][(work >> 16) & 0x3f]

		  ^  DES_TABLE::sbox[0][(work >> 24) & 0x3f];

		work = r ^ aKey[4*i+1];

		l ^= DES_TABLE::sbox[7][(work) & 0x3f]

		  ^  DES_TABLE::sbox[5][(work >> 8) & 0x3f]

		  ^  DES_TABLE::sbox[3][(work >> 16) & 0x3f]

		  ^  DES_TABLE::sbox[1][(work >> 24) & 0x3f];

		work = rotrFixed(l, 4U) ^ aKey[4*i+2];

		r ^= DES_TABLE::sbox[6][(work) & 0x3f]

		  ^  DES_TABLE::sbox[4][(work >> 8) & 0x3f]

		  ^  DES_TABLE::sbox[2][(work >> 16) & 0x3f]

		  ^  DES_TABLE::sbox[0][(work >> 24) & 0x3f];

		work = l ^ aKey[4*i+3];

		r ^= DES_TABLE::sbox[7][(work) & 0x3f]

		  ^  DES_TABLE::sbox[5][(work >> 8) & 0x3f]

		  ^  DES_TABLE::sbox[3][(work >> 16) & 0x3f]

		  ^  DES_TABLE::sbox[1][(work >> 24) & 0x3f];

		}

	}

TInt CDES::BlockSize() const

	{

	return KDESBlockBytes;

	}

TInt CDES::KeySize() const

	{

	return KDESKeyBytes;

	}

CDES::~CDES()

	{

	delete iKey;

	}

void CDES::ConstructL(const TDesC8& aKey, TBool /*aCheckWeakKey*/)

	{

	assert(aKey.Size() == KDESKeyBytes);

	iKey = aKey.AllocL();

	SetKey(aKey, iK1);

	}

CDES::CDES()

	{

	}

typedef TUint8 TKeyDES[KDESKeyBytes];

const TInt KKnownWeakKeysCount = 16;

const TKeyDES weak_keys[KKnownWeakKeysCount] =

	{

	/* weak keys */

	{0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00},

	{0xFE,0xFE,0xFE,0xFE,0xFE,0xFE,0xFE,0xFE},

	{0x1E,0x1E,0x1E,0x1E,0x0E,0x0E,0x0E,0x0E},

	{0xE0,0xE0,0xE0,0xE0,0xF0,0xF0,0xF0,0xF0},

	{0x00,0xFE,0x00,0xFE,0x00,0xFE,0x00,0xFE},

	{0xFE,0x00,0xFE,0x00,0xFE,0x00,0xFE,0x00},

	{0x1E,0xE0,0x1E,0xE0,0x0E,0xF0,0x0E,0xF0},

	{0xE0,0x1E,0xE0,0x1E,0xF0,0x0E,0xF0,0x0E},

	{0x00,0xE0,0x00,0xE0,0x00,0xF0,0x00,0xF0},

	{0xE0,0x00,0xE0,0x00,0xF0,0x00,0xF0,0x00},

	{0x1E,0xFE,0x1E,0xFE,0x0E,0xFE,0x0E,0xFE},

	{0xFE,0x1E,0xFE,0x1E,0xFE,0x0E,0xFE,0x0E},

	{0x00,0x1E,0x00,0x1E,0x00,0x0E,0x00,0x0E},

	{0x1E,0x00,0x1E,0x00,0x0E,0x00,0x0E,0x00},

	{0xE0,0xFE,0xE0,0xFE,0xF0,0xFE,0xF0,0xFE},

	{0xFE,0xE0,0xFE,0xE0,0xFE,0xF0,0xFE,0xF0}

	};

void CDES::SetKey(const TDesC8& aKey, TUint32* aKeyBuffer)

	{

	TInt i=0, j=0, l=0, m=0;

//	Form a byte array from aKey, taking endianess into account (little->big)	

	TUint8 key[8];								//	For big endian byte array	

	Mem::Copy(&key, &aKey[0], 8);

	TUint8 buffer[56+56+8];

	TUint8* const pc1m = &buffer[0];			/* place to modify pc1 into */

	TUint8* const pcr = pc1m + 56;				/* place to rotate pc1 into */

	TUint8* const ks = pcr + 56;

	for (j=0; j<56; j++) 

		{/* convert pc1 to bits of key */

		l = DES_TABLE::pc1[j]-1;				/* integer bit location  */

		m = l & 07;								/* find bit              */

		pc1m[j]=(key[l>>3] &					/* find which key byte l is in */

			bytebit[m])							/* and which bit of that byte */

			? (TUint8)1 : (TUint8)0;			/* and store 1-bit result */

		}

	for (i=0; i<16; i++) 

		{/* key chunk for each iteration */

		Mem::FillZ(ks,8);							/* Clear key schedule */

		for (j=0; j<56; j++)

		/*	rotate pc1 the right amount */

			pcr[j] = pc1m[(l=j+DES_TABLE::totrot[i])<(j<28? 28 : 56) ? l: l-28];

		/* rotate left and right halves independently */

		for (j=0; j<48; j++)

			{/* select bits individually */

			/* check bit that goes to ks[j] */

			if (pcr[DES_TABLE::pc2[j]-1])

				{/* mask it in if it's there */

				l= j % 6;

				ks[j/6] |= bytebit[l] >> 2;

				}

			}

		/* Now convert to odd/even interleaved form for use in F */

		(*(aKeyBuffer+(2*i))) = ((TUint32)ks[0] << 24)

			| ((TUint32)ks[2] << 16)

			| ((TUint32)ks[4] << 8)

			| ((TUint32)ks[6]);

		(*(aKeyBuffer+(2*i+1))) = ((TUint32)ks[1] << 24)

			| ((TUint32)ks[3] << 16)

			| ((TUint32)ks[5] << 8)

			| ((TUint32)ks[7]);

		}

	}

void CDES::Reset()

	{

	SetKey(*iKey, iK1);

	}

/* CDESEncryptor */

EXPORT_C CDESEncryptor* CDESEncryptor::NewL(const TDesC8& aKey, 

	TBool aCheckWeakKey)

	{

	CDESEncryptor* me = CDESEncryptor::NewLC(aKey, aCheckWeakKey);

	CleanupStack::Pop(me);

	return (me);

	}

EXPORT_C CDESEncryptor* CDESEncryptor::NewLC(const TDesC8& aKey, 

	TBool aCheckWeakKey)

	{

	CDESEncryptor* me = new (ELeave) CDESEncryptor();

	CleanupStack::PushL(me);

	me->ConstructL(aKey, aCheckWeakKey);

	// DES only used 7 bits out of every key byte

	TCrypto::IsSymmetricWeakEnoughL(BytesToBits(aKey.Size()) - aKey.Size());

	return (me);

	}

CDESEncryptor::CDESEncryptor()

	{

	}

/* CDESDecryptor */

EXPORT_C CDESDecryptor* CDESDecryptor::NewL(const TDesC8& aKey, 

	TBool aCheckWeakKey)

	{

	CDESDecryptor* me = CDESDecryptor::NewLC(aKey, aCheckWeakKey);

	CleanupStack::Pop(me);

	return (me);

	}

EXPORT_C CDESDecryptor* CDESDecryptor::NewLC(const TDesC8& aKey, 

	TBool aCheckWeakKey)

	{

	CDESDecryptor* me = new (ELeave) CDESDecryptor();

	CleanupStack::PushL(me);

	me->ConstructL(aKey, aCheckWeakKey);

	// DES only used 7 bits out of every key byte

	TCrypto::IsSymmetricWeakEnoughL(BytesToBits(aKey.Size()) - aKey.Size());

	return (me);

	}

CDESDecryptor::CDESDecryptor()

	{

	}

void CDESDecryptor::SetKey(const TDesC8& aKey, TUint32* aKeyBuffer)

	{

	CDES::SetKey(aKey, aKeyBuffer);

	ReverseKeySchedule(iK1);

	}

EXPORT_C TBool CDES::IsWeakKey(const TDesC8& aKey)

	{

	TKeyDES key;

	TInt index = 0;

	//Reset parity bits

	for(; index < KDESKeyBytes; index++)

		{

		key[index] = aKey[index] & 0xFE;

		}

	TBool weak = EFalse;	

	//Compare key with potential weak keys without parity	

	for (index=0; index < KKnownWeakKeysCount; index++)

		{

		if (Mem::Compare(weak_keys[index], KDESKeyBytes, &key[0], KDESKeyBytes)==0)

			{

			weak = ETrue;

			break;

			}

		}

	return weak;

	}